ABSTRACT It is assumed, as conventional wisdom, that the green building design features are effective in reducing allergens and toxic substances within the home. Scientifically credible evidence is needed as to the extent to which green-built, low-income housing actually reduces exposures to these hazards when compared to standard-built, low-income housing. Green housing utilizes various strategies to reduce environmental contaminants. It is hypothesized that these strategies will lead to 1) lower levels of environmental contaminants in green housing compared to those of control housing, and 2) lower levels of related biomarkers of exposure in the residents of green vs. control housing. The reduction of irritants and allergens in green vs. control housing may result in improved asthma morbidity among residents of green housing. Specifically, we hypothesize that children with asthma (ages 7-12 years) who reside in green housing will have lower asthma morbidity, adjusting for environmental tobacco smoke (ETS) exposure. This hypothesis will be tested through two specific aims: (1) To conduct an exposure assessment of chemical and biological contaminants, pesticides, volatile organic compounds (VOCs), fungi, indoor allergens (in terms of variety and concentration) in green and comparison housing, and (2) To examine the association between residing in green vs. comparison housing and asthma morbidity (e.g., symptoms, emergency department visits, use of medications, lost school/work days) of children with doctor-diagnosed asthma (ages 7-12 years). Environmental and clinical assessments will be conducted in 32 green renovated apartments at baseline (immediately after renovation) and at 6 and 12 months after renovation. Parallel assessments will be conducted in 32 non-renovated apartments. The study in Cincinnati is part of a nationwide Green Housing study conducted in close partnership with the Centers for Disease Control and Prevention (CDC) and U.S. Department of Housing and Urban Development (HUD). Cincinnati is one of the first metropolitan areas being assessed in this multicenter study; Boston, Massachusetts is being simultaneously assessed by the Harvard School of Public Health. The nationwide multi-site design will provide contextual information to understand which green building rehabilitation practices are associated with health not only regionally, but nationally. This elucidation then could inform policy about which green components should be implemented without regard to locality, and which components should be modified under certain circumstances (e.g., region or housing type).